Magnetic Condition Flat Core/Shell Nanoparticles

In terms two-phase nanoparticles model, dependence equilibrium position of magnetic moments of parameters size and elongation nanoparticles core is investigated. Phase diagrams of magnetic states were shown and determine geometrical parameters core, in equilibrium states.

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Dependence of Relaxation Time on the Core Size Two-Phase Nanoparticles Magnetite/Titanomagnetite

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.752-753.418 ◽

2015 ◽

Vol 752-753 ◽

pp. 418-421

Author(s):

Ilia Iliushin ◽

Leonid Afremov ◽

Sergey Anisimov

Keyword(s):

Relaxation Time ◽

Blocking Temperature ◽

Exchange Constant ◽

Core Shell ◽

Core Size ◽

Shell Nanoparticles ◽

Two Phase ◽

The Core ◽

Core Shell Nanoparticles ◽

Model Nanoparticles

In this paper, depending of the blocking temperature on magnetite core size for core/shell nanoparticles has been carried out using our theoretical model. Nanoparticles has size of 100nm, and magnetite core increases from 0nm to 100nm. Systems were studied with different values of exchange constant. The data obtained indicate that exchange constant increases the blocking temperature. However, the sign of the constant does not matter.

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Effect of Magnetic and Geometric Properties on the Time of Magnetic Relaxation of Superparamagnetic Core-Shell Nanoparticles

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.821-822.1336 ◽

2013 ◽

Vol 821-822 ◽

pp. 1336-1340

Author(s):

Leonid L. Afremov ◽

Ilia Ilyushin

Keyword(s):

Relaxation Time ◽

Magnetic Relaxation ◽

Superparamagnetic Nanoparticles ◽

Exchange Constant ◽

Core Shell ◽

Shell Nanoparticles ◽

Interphase Interaction ◽

Geometric Properties ◽

Core Shell Nanoparticles ◽

Magnetic States

Within the frame of two-phase superparamagnetic nanoparticles the effect of magnetic and geometric properties of superparamagnetic nanoparicles on the time of their magnetic relaxation has been defined. With increasing of volume, elongation of nanoparticle and relative volume of inclusions the time of relaxation grows rapidly. Metastability conditions of magnetic states have been developed. Growth of exchange constant magnitude of interphase interaction results in increasing of relaxation time regardless of exchange constant sign. Keywords: superparamagnetic particles, core-shell nanoparticles, relaxation time, magnetic states, critical field, metastable magnetic states, interphase exchange interaction.

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The effects of the size and structure on magnetic behavior of core/shell nanoparticles

International Journal of Modern Physics B ◽

10.1142/s021797921950125x ◽

2019 ◽

Vol 33 (13) ◽

pp. 1950125

Author(s):

Long V. Le ◽

Vinh V. Le ◽

Quy Q. Ho

Keyword(s):

Phase Diagrams ◽

Exchange Coupling ◽

Magnetic Behavior ◽

Md Simulations ◽

Core Shell ◽

Shell Nanoparticles ◽

Mc Simulation ◽

Amorphous States ◽

Core Shell Nanoparticles ◽

Hexagonal Closed Packed

Molecular dynamics (MD) simulations have been employed to simulate the structure of Ni nanoparticles (NPs). These NPs consist of 500, 1372, 2916 and 5324 atoms. Various structures of these NPs, consisting of faced-centered cubic (fcc), hexagonal closed packed (hcp), icosahedral (ico) and amorphous states, have been simulated by changing the cooling rate from 2000 to 300 K. The models of mixed core/shell spin (1, 3/2) have been set based on the NPs. Monte Carlo (MC) simulation has been applied to investigate the magnetic behavior and phase diagrams of the models. We have found that the structure of the models plays important role on the characteristic phase diagrams. The effects of the atomic number as well as the exchange coupling J[Formula: see text]/J[Formula: see text] (J[Formula: see text] — the shell coupling and J[Formula: see text] — the core coupling) on the thermal and magnetic behaviors of the models have been presented and discussed. The phase diagrams in k[Formula: see text]T/J[Formula: see text]−J[Formula: see text]/J[Formula: see text] plane also have been observed by changing the structure and the number atoms of the models.

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